let obj = {
    pageScope : {

    }
}

let _obj = new Proxy(obj,{
    get (target,key) {
        return target[key]
    },
    set (target,key,value) {
        if (key != 'pageScope') {
            return false
        }
        target[key] = value
    }
})
_obj.a = 1
console.log('obj',obj)